Derangements and Generalizations: A Counting Note on the Matching Problem

Fuente: arXiv
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Main Author: Luciano, Antoine
Format: Preprint
Published: 2025
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_version_ 1866911230917083136
author Luciano, Antoine
author_facet Luciano, Antoine
contents We give a concise historical background to Montmort's matching problem and its modern variants such as the hat-check problem, then develop a unified counting framework for fixed-point-free allocations. Using elementary recurrence and inclusion-exclusion arguments, we derive closed forms for derangements, rectangular injections, and partial l-matchings, and we combine them into a single formula. We also provide exact counts for the number of fixed points and Poisson limit laws. This note thus offers a compact, self-contained synthesis linking classical results with their two principal generalizations in a single scheme.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21753
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Derangements and Generalizations: A Counting Note on the Matching Problem
Luciano, Antoine
History and Overview
Combinatorics
We give a concise historical background to Montmort's matching problem and its modern variants such as the hat-check problem, then develop a unified counting framework for fixed-point-free allocations. Using elementary recurrence and inclusion-exclusion arguments, we derive closed forms for derangements, rectangular injections, and partial l-matchings, and we combine them into a single formula. We also provide exact counts for the number of fixed points and Poisson limit laws. This note thus offers a compact, self-contained synthesis linking classical results with their two principal generalizations in a single scheme.
title Derangements and Generalizations: A Counting Note on the Matching Problem
topic History and Overview
Combinatorics
url https://arxiv.org/abs/2510.21753